15.1 Life in the Earth System · 15.1 Life in the Earth System Biotic and abiotic factors interact in the biosphere. • All four Earth systems are interconnected. • The Gaia hypothesis

15.1 Life in the Earth System

KEY CONCEPT The biosphere is one of Earth’s four interconnectedsystems.


The biosphere is the portion of Earth that is inhabited bylife.

• The biosphere includes all ecosystems.

– one of Earth’s systems

– includes the biota, all the living things in the biosphere


• There are three other Earthsystems.

– hydrosphere—water, ice,and water vapor

– atmosphere—airblanketing Earth’s solidand liquid surface

– geosphere—geologicfeatures above andbelow Earth’s surface


Biotic and abiotic factors interact in the biosphere.

• All four Earth systemsare interconnected.

• The Gaia hypothesisconsiders Earth as akind of living organism.

– Earth systemsinteract to yield abiosphere capableof supporting life.

– It was developed byJames Lovelockand Lynn Margulis.

15.2 Climate

KEY CONCEPT Climate is a key abiotic factor that affects thebiosphere.

15.2 Climate

Climate is the prevailing weather of a region.

• Climate is the long-termpattern of weatherconditions.– average temperature– precipitation– relative humidity

• Key factors shape an area’sclimate.

– temperature

– sunlight– water– wind

15.2 Climate

• A microclimate is the climate of a small specific placewithin a larger area.

15.2 Climate

Earth has three main climate zones.

• The three main zones are the polar, tropical, andtemperate climates.

– polar climate: the far northernand southern regions ofEarth

– tropical zone: surrounds the equator

– temperate zone: the wide area in betweenthe polar and tropical zones

15.2 Climate

• The angle of the Sun’s rays help determine an area’sclimate.

temperatetemperate

polarpolar

tropicaltropical

temperatetemperate

polarpolar

90 N

15.2 Climate

• Earth’s tilt on its axis plays a role in seasonal change.

• Solar heating causes movements in both water and air.– wind– ocean currents

• Earth’s rotation also has effects on the winds and currents

15.2 Climate

• Landmasses shape inlandclimates. – larger changes in

temperatures– less precipitation

• Oceans shape coastalclimates.– smaller changes in

temperatures

– higher humidity

– more precipitation

15.2 Climate

• Mountains have an effect on climate.

western slope eastern slope

– Precipitation occurs on the side of the mountainfacing the wind.

– On the downwind side, drier and cooler air producea rain shadow.

– A rain shadow is an area of decreased precipitation.

15.2 Climate

• Many organisms survive in a specific climate due to theiradaptations.

15.3 Biomes

KEY CONCEPT Biomes are land-based, global communities oforganisms.

15.3 Biomes

Earth has six major biomes.

• A biome is a major community of organisms.

15.3 Biomes

• Tropical rain forestbiomes produce lushforests.– warm temperature– abundant

precipitation all year

Source: World Meteorological Organization

15.3 Biomes

• Grassland biomes are where the primary plant life isgrass.

Rapid City, South Dakota

Source: National Oceanic Atmospheric Administration

15.3 Biomes

– Temperate grasslands are dry and warm during thesummer; most precipitation falls as snow.

• Grassland biomes are where the primary plant life isgrass.

– Tropical grasslands are warm through the year, withdefinite dry and rainy seasons.

15.3 Biomes

• Desert biomes arecharacterized by a very aridclimate.– very low amount of

precipitation– four types: hot, semi-

arid, coastal, and cold

Tucson, Arizona


15.3 Biomes

• Temperate forest biomes include deciduous forests andrain forests.– Temperate deciduous forests have hot summers and

cold winters.

– Deciduous trees are the dominant plant species.


Burlington, Vermont

15.3 Biomes

– Deciduous trees are the dominant plant species.– The temperate rain forests have a long wet season and

relatively dry summer.

• Temperate forest biomes include deciduous forests andrain forests.– Temperate deciduous forests have hot summers and

cold winters.

– Ferns and mosscover the forestfloor.

15.3 Biomes

• The taiga biome is locatedin cooler northern climates.– boreal forest– long winters and short

summers– small amount of

precipitationSource: Environment Canada

Banff, Canada

15.3 Biomes

• The tundra biome is foundin the far northern latitudeswith long winters.– winter lasts 10 months– limited precipitation– permafrost

Barrow, Alaska


15.3 Biomes

• Minor biomes, such as chaparral, occur globally on asmaller scale.

15.3 Biomes

Polar ice caps and mountains are not considered biomes.

• Polar ice caps have no soil, therefore no plant community.

• The climate and organisms found on mountains change asthe elevation changes.

15.4 Marine Ecosystems

KEY CONCEPT Marine ecosystems are global.


– neritic zone—fromintertidal zone tocontinental shelf

– bathyal zone—from neritic zone tobase of continentalshelf

– abyssal zone –liesbelow 2000 m

The ocean can be divided into zones.

• Ocean zones can be determined by their distance fromshoreline and water depths.– intertidal zone—between low and high tide

intertidal zoneneritic zone

bathmatzone

abyssalzone


• The neritic zone harbors more biomass than any otherzone.

• Plankton make up most of the biomass.– zooplankton

– phytoplankton


Coastal waters contain unique habitats.

• Coral reefs are found in warm waters.– tropical climate zone

– great amount of biomass


• Kelp forests are found incold, nutrient-rich waters. – large communities of

seaweed– great amount of

biomass

15.5 Estuaries and Freshwater Ecosystems

KEY CONCEPT Freshwater ecosystems include estuaries as wellas flowing and standing water.


Estuaries are dynamic environments where rivers flowinto the ocean.

• An estuary is a partially enclosed body of water.

– mixture of fresh water with salt water– Chesapeake Bay– Louisiana bayous


• Estuaries are highly productive ecosystems.• Estuaries provide a protected refuge for many species.

– birds migration– spawning grounds

• Estuaries are primarily threatened by land development.


Freshwater ecosystems include moving and standingwater.

• A watershed is a region of land that drains into a body ofwater.

• Ecosystems may be different along a river’s course


• Wetlands are among the most productive ecosystems.– provide a home for many species

– filter dirty water

– renew underground water supply

• Some animals have adaptations suited to the freshwaterthey inhabit.


Ponds and lakes share common features.

• Freshwater bodies are divided into three zones.– littoral zone– limnetic zone– benthic zone


• All lakes “turn over” periodically.– Turn over happens due to changes in density.– In both autumn and spring, surface water flows

downward and bottom water flows upward.

– The upwelling brings up nutrients.

15.1 Life in the Earth System · 15.1 Life in the Earth System Biotic and abiotic factors interact in the biosphere. • All four Earth systems are interconnected. • The Gaia hypothesis

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